Guidewire for cannula placement

ABSTRACT

A guidewire for backloading and inserting a percutaneous pump affixed to a cannula includes a proximal section made of a first material, with a first diameter, a rounded proximal end, and a distal end. The guidewire also includes a distal section made of a second material, with a second diameter which is greater than the first diameter, a distal end, and a proximal end abutting the distal end of the proximal section. The first material of the proximal section is selected to be softer than a material of the percutaneous pump to reduce damage to the pump during backloading. The distal section of the guidewire is configured to be stiffer than the proximal section to insert the percutaneous pump in a desired location without damaging the guidewire.

This application relates to U.S. Pat. No. 6,007,478, the content ofwhich is hereby incorporated herein by reference in its entirety.

BACKGROUND

A blood pump, such as a percutaneous intracardiac blood pump assembly,is introduced in the heart to deliver blood from the heart into anartery, such as the pulmonary artery. When deployed in the heart, ablood pump assembly pulls blood from the left ventricle of the heart andexpels blood into the aorta, or pulls blood from the right ventricle andexpels blood into the pulmonary artery, through a cannula. Blood pumpassemblies are introduced surgically or percutaneously during a cardiacprocedure through the vascular system. In one common approach, pumpassemblies are inserted by a catheterization procedure through thefemoral artery using a guidewire.

An introducer is inserted into the femoral artery through an arteriotomyto create an insertion path. A placement guidewire is then advanceddistal end first through the sheath into the artery. Once the guidewirehas been inserted into the artery, the pump assembly, including a pumpand a cannula, is backloaded onto the proximal end of the guidewire andpushed along the guidewire and into the patient. The pump assembly maythen be used in conjunction with a catheter.

As defined herein, backloading involves inserting the proximal end ofthe guidewire, which remains outside the patient, into the distal end ofthe catheter and then advancing the catheter distally over the wire.Backloading the pump assembly allows the guidewire to remain in positionwithin the patient while different size catheters or sheaths areinserted and removed during the course of a procedure. But the cannulaof the pump assembly can have a tortuous shape, or the cannula can bestiff. In these cases, the guidewire may not be stiff enough to allowbackloading of the pump through to the pulmonary valve, and as a resultthe cannula of the pump may displace the guidewire out of the pulmonaryvalve. For example, for systems delivering blood from the inferior venacava to an opening in the pulmonary artery, the cannula of the pump maybe a 3D shape with two “S” turns in different planes. This can makebackloading and insertion of the pump assembly into a patientparticularly difficult.

SUMMARY

Systems, methods, and devices for an improved guidewire for cannulaplacement are presented. The improved guidewire facilitates insertion ofthe guidewire through a heart pump without damaging the pump. Thisimproved guidewire is particularly helpful for pumps having complex ortortuous geometries, such as the IMPELLA RP pump or any other pumpadapted for use in the right ventricle (e.g., between the inferior venacava and the pulmonary artery).

The improved guidewire disclosed herein can be inserted into thearterial system of a patient through an arteriotomy. The guidewireincludes a first distal section, an intermediate pump delivery section,and a backloading proximal section. The first distal section, isinserted first into the arterial system of the patient. The first distalsection is flexible and has a rounded end which allows a physician toinsert the guidewire with minimal trauma to the patient. For example,during insertion the first distal section of the guidewire may come intocontact with the walls of the patient's artery, or with a lumen placedinside the patient's artery. Thus, use of a material with low frictionand high flexibility for the first distal section, such as a plastic orpolymer, can reduce trauma and discomfort to the patient.

The intermediate pump delivery section, is connected to the first distalsection. While the first distal section of the guidewire facilitatesinsertion in the patient, the intermediate pump delivery sectionfacilitates backloading of a pump assembly onto the guidewire. The pumpassembly includes a pump affixed to a cannula. During backloading, theproximal end of the guidewire which remains outside the patient must beinserted into the pump and through the cannula, before the pump andcannula can be pushed along the guidewire until reaching the desiredsite. Depending on the application, the cannula may take differentshapes. For example, in the case of some pumps for the right ventricle(e.g., the IMEPLLA RP pump), the pump is located at one end of a cannulawith a complex three-dimensional shape, including two “S” bends indifferent planes. Having an intermediate pump delivery section of theguidewire which is stiffer than the first distal section facilitatesbackloading of the stiff cannula and minimizes the risk of the stiffcannula displacing the guidewire. The pump delivery section can have alarger diameter than the first distal section and can be made of astiffer material.

The intermediate section of the guidewire is connected to thebackloading proximal section. While the intermediate section, alsoreferred to as intermediate pump delivery section, facilitates guidingthe pump assembly into position without displacing the guidewire, thebackloading proximal section minimizes damage to the pump during thebackloading process. Due to its softness and flexibility relative to theintermediate pump delivery section, the backloading proximal section canbe inserted into the pump without damaging the pump. This isparticularly helpful because the small size of the pump and theguidewire routinely complicate initiation of the backloading process.Inserting the guidewire into the pump through the small gap between theimpeller blades and the housing may require several attempts.

In some implementations, the first distal section, the intermediate pumpdelivery section, and the backloading proximal section of the guidewirehave different stiffnesses due to differences in materials, structures,geometries, or a combination thereof.

The guidewire disclosed herein provides a number of possible advantages.The guidewire is flexible enough at its proximal end to pass through thepump without unnecessary damage. At the same time, the guidewire isstiff enough at its distal end to guide the cannula into place duringbackloading without being displaced. This can help avoid multipleinsertions of the guidewire into the patient and minimizes the risk ofdamage to the patient's arterial system.

In one aspect, a system for inserting a percutaneous pump includes apercutaneous pump, a cannula and a guidewire. The cannula has a cannuladiameter, a proximal inlet, and a distal outlet. The percutaneous pumpis located at, and affixed to, the distal outlet of the pump. Theguidewire includes a proximal section with a first stiffness and havinga first diameter, and a distal section connected to the proximalsection, the distal section with a second stiffness and a seconddiameter which is greater than the first diameter. The distal section isstiffer than the proximal section to insert the cannula and position itin a desired location without displacing the guidewire.

In certain implementations, the proximal section of the guidewire uses afirst material which is softer than a material of the percutaneous pumpto reduce damage to the percutaneous pump during backloading of thecannula onto the guidewire.

In certain implementations, the proximal section is made of a firstmaterial with the first stiffness and the distal section is made of asecond material with the second stiffness.

In certain implementations, the proximal section is made of a firststructure with the first stiffness and the distal section is made of asecond structure with the second stiffness.

In certain implementations, the guidewire includes a distal tip which isconnected to a distal end of the distal section.

in certain implementations, the cannula has a three-dimensional shapewith a first “S” bend in a first plane, and a second “S” bend in asecond plane, where the second plane is different from the first plane.

In certain implementations, the proximal section has a rounded proximalend made of a third material.

In certain implementations, a ratio of a diameter of the proximalsection over a diameter of the distal section is 0.72.

In certain implementations, a stiffness of the proximal section is loweran a stiffness of the distal section.

in certain implementations, the proximal section extends over 40 to 75%of a total length of the guidewire.

In another aspect, a guidewire for backloading and inserting apercutaneous pump includes a proximal section and a distal section. Theproximal section is made of a first material and has a first diameter.The proximal section includes a rounded proximal end and a distal end.The distal section is made of a second material and has a seconddiameter. The second diameter of the distal section is greater than thefirst diameter of the proximal section. A proximal end of the distalsection abuts the distal end of the proximal section. The first materialof the proximal section is selected to be softer than a material of thepercutaneous pump to reduce damage to the pump housing or blades duringbackloading of the percutaneous pump onto the guidewire. The distalsection is configured to be stiffer than the proximal section such thatthe percutaneous pump can be inserted and moved to a desired locationwithout displacing the guidewire.

In some implementation, a stiffness of the second material is greaterthan a stiffness of the first material.

In some implementation, the proximal section is made of a firststructure and has a first stiffness and the distal section is made of asecond structure and has a second stiffness.

In some implementation, the proximal section is made of a firststructure and has a first stiffness, and the distal section is made of asecond structure and has a second stiffness.

In certain implementations, a stiffness of the proximal section is lowerthan a stiffness of the distal section.

In certain implementations, the proximal section is coated and thedistal section is not coated.

In certain implementations, a ratio of a diameter of the proximalsection over a diameter of the distal section is 0.72.

In certain implementations, the proximal end extends over 40 to 75% of atotal length of the guidewire.

In certain implementations, the proximal section includes a distal tipwhich is connected to a distal end of the distal section.

In certain implementations, the rounded proximal end of the proximalsection is made of a third material.

In another aspect, a method for inserting a percutaneous pump includesinserting a guidewire into a cannula through a distal end of the cannulawhich supports the percutaneous pump, and pushing the guidewire throughthe percutaneous pump and cannula. The guidewire includes a proximalsection with a first stiffness and a first diameter, and a distalsection connected to the proximal section, the distal section with asecond stiffness and a second diameter greater than the first diameter.The distal section is stiffer than the proximal section to insert thecannula in a desired location without displacing the guidewire.

Variations and modifications will occur to those of skill in the artafter reviewing this disclosure. The disclosed features may beimplemented, in any combination and subcombination (including multipledependent combinations and subcombinations), with one or more otherfeatures described herein. The various features described or illustratedabove, including any components thereof, may be combined or integratedin other systems. Moreover, certain features may be omitted or notimplemented.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects and advantages will be apparent uponconsideration of the following detailed description, taken inconjunction with the accompanying drawings, in which like referencecharacters refer to like parts throughout, and in which:

FIG. 1 shows an illustrative embodiment of a cannula assembly;

FIG. 2 shows a lateral cross-section of a conventional guidewire;

FIGS. 3 and 4 show illustrative damage to blades of a percutaneous pump,resulting from backloading the percutaneous pump on a conventionalguidewire;

FIG. 5 shows a lateral cross-section of a first illustrative embodimentof a guidewire;

FIG. 6 shows a lateral cross-section of a second illustrative embodimentof a guidewire;

FIG. 7 shows a lateral cross-section of a third illustrative embodimentof a guidewire;

FIG. 8 shows a lateral cross-section of a fourth illustrative embodimentof a guidewire;

FIGS. 9 and 10 show tables of data related to properties of theguidewire in FIG. 2 and a guidewire in any of FIGS. 2-8;

FIG. 11 shows a percutaneous pump being backloaded on a guidewireaccording to one of the illustrative embodiments of FIGS. 5-8; and

FIG. 12 shows an illustrative process for inserting a guidewire.

DETAILED DESCRIPTION

To provide an overall understanding of the systems, methods, and devicesdescribed herein, certain illustrative embodiments will be described.Although the embodiments and features described herein are specificallydescribed for use in connection with a percutaneous blood pump systemfor the right ventricle, it will be understood that all the componentsand other features outlined below may be combined with one another inany suitable manner and may be adapted and applied to blood pump systemsfor the left ventricle or other types of cardiac therapy and cardiacassist devices, including balloon pumps, cardiac assist devicesimplanted using a surgical incision, and the like.

The systems, methods, and devices described herein provide a guidewirehaving a first proximal section and a second distal section such that acannula can be inserted over a guidewire without displacing theguidewire and without damaging a pump coupled to the cannula. Theproximal section of the guidewire is less stiff than the distal sectionof the guidewire due to the geometry or the material of the proximalsection. For example, the proximal section of the guidewire may have adiameter which is smaller than a diameter of the distal section. Inanother example, the proximal section of the guidewire may be made of amaterial which is less stiff than a material of the distal section ofthe guidewire. In yet another example, the proximal section of theguidewire may have a structure which is less stiff than a structure ofthe distal section of the guidewire. The lower stiffness of the proximalsection, relative to the stiffness of the distal section, allowsphysicians to more easily insert the guidewire into a percutaneous pumplocated at a distal end of a cannula. In particular, physicians may beable to insert the proximal section of the guidewire into the gaplocated between the housing and the blades of the percutaneous pumpwithout damaging the blades, and without damaging or rupturing thehousing.

FIG. 1 shows an illustrative embodiment of a blood pump assembly 100.The blood pump assembly 100 includes a pump 101, a pump housing 103, aproximal end 105, a distal end 107, a cannula 108, an impeller 109, anextension 102, a catheter 112, an inlet area 110, an outlet area 106,and blood exhaust apertures 117. The catheter 112 is connected to theinlet area 110 of the cannula 108. The inlet area 110 is located nearthe proximal end 105 of the cannula, and the outlet area 106 is locatedtoward the distal end 107 of the cannula 108. The inlet area 110includes a pump housing 103 with a peripheral wall 111 extending about arotation axis 113 of the impeller blades 115, positioned radiallyoutward of the inner surface with respect to the rotation axis 113 (notshown) of the impeller 109 (not shown). The impeller 109 is rotatablycoupled to the pump 101 at the inlet area 110 adjacent to the bloodexhaust apertures 117 formed in the wall 111 of the pump housing 103.The pump housing 103 may be composed of a metal in accordance withimplementations. The extension 102, also referred to as a “pigtail,” isconnected to the distal end 107 of the cannula 108 and assists withstabilizing and positioning the blood pump assembly 100 into the correctposition in the heart. The pigtail 102 is configurable from a straightto a partially curved configuration. The pigtail 102 may be composed, atleast in part of a flexible material, and may have dual stiffness,

The cannula 108 has a shape which matches the anatomy of the rightventricle of a patient. In this exemplary embodiment, the cannula has aproximal end 105 arranged to be located near the patient's inferior venacava, and a distal end 107 arranged to be located near the pulmonaryartery. The cannula 108 includes a first segment S1 extending from theinflow area to a point B between the inlet area 110 and the outlet area106. The cannula 108 also includes a second segment S2 extending from apoint C, which is between the inlet area 110 and the outlet area 106, tothe outlet area 106. In some implementations B and C may be at the samelocation along cannula 108. The first segment S1 of the cannula forms an‘S’ shape in a first plane. In some implementations, segment S1 can havecurvatures between 30 degrees and 180 degrees. The second segment S2 ofthe cannula forms an ‘S’ shape in a second plane. In someimplementations, segment S2 can have curvatures between 30 degrees and180 degrees (e.g., 40°, 50°, 60°, 70°, 80°, 90°, 100°, 110°, 120°, 130°,140°, 150°, 160°, or 170°). The second plane can be different from thefirst plane. In some implementations, the second plane is parallel oridentical to the first plane.

In some implementations, the blood pump assembly 100 is insertedpercutaneously^(,) through the femoral artery and into the right tricle,Alternatively, in some implementations the blood pump assembly 100 maybe inserted percutaneously through the femoral artery and into the leftventricle. When properly positioned, the blood pump assembly 100delivers blood from the inlet area 110, which sits inside the patient'sleft ventricle, through the cannula 108, to the blood exhaust apertures117 of the pump housing 103 positioned in the ascending aorta.

FIG. 2 shows a lateral cross-section of a conventional guidewire 200.The conventional guidewire includes a distal section 210, a distal tip212, a coil wire 214, a core wire 216, a transition region 218, aproximal section 220, a proximal end 222, and a transition section 218.The coil wire 214 surrounds the core wire 216. The core wire 216 has adiameter which decreases from the transition region 218 to the tip ofthe distal section 212. The distal section 210 has a length L2, which isbetween 25-50% of the total length of the core wire 216. The core wire216 also includes a proximal section 220, extending between a proximalend 4222 and the transition section 218. The proximal section 220 has aconstant diameter. The proximal section has a length between 75-50% ofthe total length of the core wire 216. The distal section 210 of thecore wire is more flexible than the proximal section of the guidewire200. This allows a physician initially placing the guidewire into apatient to minimize damage to the arterial system of the patient.

FIGS. 3 and 4 show illustrative damage to a blade of a percutaneouspump. Exemplary blades 310 and 430 include portions 320 and 440 whichwere scratched or dented or both by attempting to insert a conventionalguidewire between the pump housing (e.g., pump housing 103 in FIG. 1)and the blades (e.g., impeller blades 115 in FIG. 1). In this example,contact between the guidewire and a pump element results in the pumpelement being scratched or indented (as shown in FIGS. 2 and 3) ratherthan in the guidewire being scratched or indented. Although onlyscratches and indentations are shown, in some cases the pump housing canbe punctured when inserting a conventional guidewire. This isparticularly a concern when using a guidewire made of a material with ahigher scratch hardness, indentation hardness or rebound hardness than amaterial used for the pump elements.

As discussed above, when a guidewire (e.g., guidewire 200 in FIG. 2) isnot stiff enough, backloading and insertion of a pump assembly (e.g.,pump assembly 100 in FIG, 1) into a patient may be particularlydifficult. Accordingly, some physicians may use a stiffer guidewire tobackload a pump (e.g., pump 101 in FIG. 1) without displacing theguidewire 200 out of the pulmonary valve. However, for particular pumps,such as the IMPELLA RP pump which is used in combination with an “S”turn cannula (e.g., cannula 108 in FIG. 1), a stiffer guidewire may notbe a viable solution. In the exemplary embodiment of the IMPELLA RP pump(e.g,, pump 101 in FIG. 1), the pump is so small that the passagebetween the pump housing (e.g., pump housing 103 in FIG. 1) and theblades of the pump (e.g., impeller blades 115 in FIG. 1) is on the orderof millimeters. Furthermore, due to their size and complexity thecomponents of the IMPELLA RP pump such as the housing (e.g., housing 103in FIG. 1) and the blades (e.g., impeller blades 115 in FIG. 1) areparticularly expensive to manufacture or replace. Any undesired contactbetween the guidewire and the pump elements, instead of having theguidewire pass straight through the aforementioned gap, can result indamage. This is particularly true for a stiff guidewire, such as aguidewire made of a material with a higher scratch hardness, indentationhardness or rebound hardness than a material used for the pump elements.A guidewire with increased stiffness throughout, either via an increaseddiameter or via material properties, could damage the housing or bladesof the pump even more than a conventional guidewire.

FIG. 5 shows a lateral cross-section of a first illustrative embodimentof a guidewire 500. The guidewire 500 includes a soft distal section510, a distal tip 512, a coil wire 514, a core wire 516, a transitionarea 518, an intermediate pump delivery section 530, a transition area532, a backloading proximal section 540, and a proximal tip 542. Thesoft distal section 510 extends between the transition area 518 and thedistal tip 512. In use, the soft distal section 510 is inserted firstinto the patient. The soft distal section 510 includes the core wire 516and the coil wire 518 coiled around the core wire 516. The core wire 516has a diameter which decreases from the transition region 518 to thedistal tip 512. Instead of a single proximal section as in the guidewire200, the guidewire 500 includes two sections, the intermediate pumpdelivery section 530 and the backloading proximal section 540. Theintermediate pump delivery section 530 and the backloading proximalsection 540 are coupled to the intermediate pump delivery section 530 bya transition area 532, The intermediate pump delivery section 530extends between the transition area 532 and the transition area 518. Theintermediate pump delivery section 530 is the portion of the guidewire500 with the widest diameter. The intermediate pump delivery section 530may have a constant diameter. In some implementations, the intermediatepump delivery section 530 is not the widest section of the guidewire.

The backloading proximal section 540 extends between the proximal tip542 and the transition section 532. The backloading proximal section 540has a constant diameter. In some implementations, the diameter of theproximal section 540 varies. The material and the structure of thebackloading proximal section 540 and the intermediate pump deliverysection 530 may be similar or the same. The backloading proximal section540 is more flexible than the intermediate pump delivery section 530because the backloading proximal section 540 has a diameter which issmaller than the diameter of the intermediate pump delivery section 530.The smaller diameter of the backloading proximal section facilitates theintroduction of the guidewire through the pump with low forces. In someimplementations, the backloading proximal section 540 is more flexiblethan the intermediate pump delivery section 530 because the backloadingproximal section 540 is formed of a material or a structure which isless stiff than the material or structure of the intermediate pumpdelivery section 530.

In certain implementations, the backloading proximal section 540 is moreflexible than the intermediate pump delivery section 530 by having amaterial composition which is 100% a material which is more flexiblethan a material of the intermediate pump delivery section 530. Theintermediate pump delivery section 530 can have a material compositionwhich is 100% a material stiffer than the material of the backloadingproximal section 540. The stiffer material of the intermediate pumpdelivery section 530 may consist of any number of materials includingbut not limited to polyurethane or resin impregnated fibers. The moreflexible material may consist of any number of materials including butnot limited to a silicone compound. In some implementations, the twodifferent materials may have the same chemical composition, butdifferent degrees of polymerization, crystallinity, or any otherproperty.

The material of the backloading proximal section 540 may be selected toreduce damage to the pump elements when there is undesired contactbetween the guidewire and any of the pump elements. In particular, thematerial of the backloading proximal section can be selected to have alower scratch hardness, indentation hardness or rebound hardness than amaterial used for the pump elements.

The proximal tip 542 of the backloading proximal section 540 is roundedand is made with or coated with a material different from the remainderof the backloading proximal section 540. For example a lubricatingcoating or lubricated material can be used for the proximal tip 542.This allows a physician to insert the proximal tip 542 and thebackloading proximal section 540 of the guidewire more easily into thepump and the cannula. In turn, these features can help reduce damage tothe blades and housing of the percutaneous pump into which the guidewireis inserted. The proximal tip 542 can be attached to the backloadingproximal section 540 by adhesive or solvent bonding, mechanicalfastening, insert molding, or any other suitable joining mechanism orcombinations thereof. Alternatively, the proximal tip 542 can beintegral to the backloading proximal section.

FIG. 6 shows a lateral cross-section of a second illustrative guidewire600 according to certain embodiments. The guidewire 600 includes a softdistal section 610, a distal tip 612, a coil wire 614, a core wire 616,a transition area 618, an intermediate pump delivery section 630, atransition area 632, a backloa.ding proximal section 640, and a proximaltip 642. The guidewire 600 includes a distal section 610 which extendsbetween the transition area 618 and the distal tip 612 and which isinserted first into the patient. The soft distal section 610 includes acore wire 616 with a diameter which decreases from the transition region638 to the distal tip 612. The soft distal section 610 also includes acoil wire 614 which is coiled around the core wire 616. The soft distalsection 610 extends over a length L2, which can be 25-50% (e.g., 30%,35%, 40%, 45%) of the total length of the guidewire 600. Preferably, thelength L2 is between 25-35% of the total length of the guidewire 600.Even more preferably, the length L2 is 30% of the total length of theguidewire 600. The guidewire 600 further comprises, instead of theproximal section 220 for example, two sections, the intermediate pumpdelivery section 630, and the backloading, proximal section 640 coupledto the intermediate pump delivery section 630 by a transition area 632.The intermediate pump delivery section 630 extends between thetransition area 632 and the transition area 618. The intermediate pumpdelivery section 630 can have a constant diameter D3, which may bebetween 0.02 and 0.03,″ with a preferred value of 0.025″. Theintermediate pump delivery section 630 has a length L3 which is between30% and 60% (e.g., 35%, 40%, 45%, 50%, 55%) of the length of theguidewire. In particular, D3 can be larger than any diameter of thebackloading proximal section 640. The backloading proximal section 640has a constant diameter D4, which may be between 0.017″ and 0.019″ witha preferred value of 0.018″. The backloading proximal section 640 canhave a length L4 which is 40-75% (e.g., 45%, 50%, 55%, 60%, 65%, 75%) ofthe length of the guidewire. For example, for a guidewire with a totallength of 260 mm, the backloading proxima section 640 has a length of atleast 100 mm.

At least one advantage of the diameter D4 of the backloading proximalsection 640 being smaller than the diameter D3 of the intermediate pumpdelivery section 630 is increased flexibility of the backloadingproximal section 640. Another advantage is a reduction in the overallweight of the guidewire. This reduction in weight is achieved becausethe backloading proximal section 640 is made lighter, and thatbackloading proximal section accounts for a substantial portion of theoverall length of the guidewire 600 (e.g., 10%, 20%, 30%, 40%, 50%, 60%,70%, 80%, 90%, or more). A lighter guidewire is easier for physicians toinsert into a patient and may also cause less damage when inserted intoa pump, such as the pump 101 of the blood pump assembly 100.

The backloading proximal section 640 may end with the proximal tip 652.The proximal tip 642 may be rounded and may be made with or coated witha different material than a material of the ba.ckloading proximalsection 640. For example a lubricating coating or lubricated materialcan be used for the proximal tip 652. This allows a physician to insertthe proximal tip and the backloading proximal section of the guidewiremore easily into the pump and the cannula. In turn, these features canhelp reduce damage to the blades and housing of the percutaneous pumpthe guidewire is being inserted into.

FIG. 7 shows a lateral cross-section of a third illustrative guidewire700 according to certain embodiments. The guidewire 700 includes a softdistal section 710, a distal tip 712, a coil wire 714, a core wire 716,a transition area 718, an intermediate pump delivery section 730, atransition area 732, a backloading proximal section 740, and a proximaltip 742. The guidewire distal section 710 extends between the transitionarea 718 and the distal tip 712, and is inserted first into the patient.The soft distal section 710 can include a core wire 716 with a diameterwhich decreases from the transition region to the distal tip 712. Thesoft distal section 710 includes the coil wire 714 which is coiledaround the core wire 716. The guidewire 700 further comprises, insteadof the proximal section 220 for example, two sections, an intermediatepump delivery section 730 and a backloading proximal section 740. Thebackloading proximal section 740 is coupled to the intermediate pumpdelivery section 730 by a transition area 732. A material of thebackloading proximal section 740 is different than a material of theintermediate pump delivery section 730. The transition area 732 can be aconical section with a first diameter equal to the diameter of thebackloading proximal section 740 and a second diameter equal to thediameter of the intermediate pump delivery section. Alternatively, thetransition 732 may be a weld. The transition 732 may be an abrupttransition resulting from joining two sections of differentflexibilities in a butt joint or a stepped joint. Alternatively, thetransition 732 can be gradual by employing a composite construction suchthat the content of a more flexible material (e.g., the main material ofthe backloading proximal section 740) gradually displaces a stiffermaterial (e.g., the main material of the intermediate pump deliverysection 730). The use of different materials for the backloadingproximal section 740 and the intermediate pump delivery section 730allows one section to be optimized for insertion (e.g., the backloadingproximal section 740) and another to be optimized for pump delivery(e.g., the intermediate pump delivery section 730). This may also reducethe guidewire's weight, cost, or both.

FIG. 8 shows a lateral cross-section of a fourth illustrative guidewire800 according to certain embodiments. The guidewire 800 includes a softdistal section 810, a distal tip 812, a coil wire 814, a core wire 816,a transition area 818, an intermediate pump delivery section 830, atransition area 832, a backloading proximal section 840, and a proximaltip 842. The guidewire distal section 810, which is inserted first intothe patient, extends between the transition area 818 and the distal tip812. The soft distal section 810 can include a core wire 816 with adiameter which decreases from the transition region 838 to the distaltip 812. The soft distal section 810 can also include a coil wire 814which is coiled around the core wire 816. The guidewire 800 furthercomprises, instead of the proximal section 220 for example, twosections, an intermediate pump delivery section 830, and a backloadingproximal section 840 coupled to the intermediate pump delivery section830 by a transition area 832. The intermediate pump delivery section 830can have a first structure which is a core wire with a constantdiameter. The backloading proximal section 840 can have a secondstructure which includes a core wire 843, and a coil wire 844. The corewire 816 can have a constant diameter. Alternatively, the core wire 843can be tapered to have a first larger diameter adjacent to thetransition area 832, and a second smaller diameter adjacent to theproximal tip 842. The coil wire 844 may be wrapped around the core wire843. Similar to the core wire 843, the coil wire 844 may have a constantdiameter, or may have a diameter which decreases from transition area832 to proximal tip 842.

The coil wire 844 can impart resistance to radial deformation and canallow the guidewire 800 to regain its original shape even afterdeformations that it may be subjected to during placement ormanipulation in the heart. The coil wire 844 may have any number ofcross-sectional shapes including but not limited to round or rectangularcross-sections. The coil wire 844 may also have varying axial densitythat varies the elasticity or flexibility of the backloading proximalsection 840.

FIGS. 9 and 10 are tables summarizing the dimensions and materialproperties of exemplary embodiments of the guidewire shown in FIGS. 2and 5-8.

FIG. 9 shows a table indicating diameter, length, function, materialsand coating for a related art guidewire (e.g. guidewire 200 in FIG. 2)and an improved guidewire with a proximal section and a distal section(e.g. guidewire in any of FIGS. 5-8). FIG. 9 indicates that the outerdiameter D1 of a related art guidewire is 0.025″ which is the same asthe outer diameter D1 of the improved guidewire distal section. FIG. 9indicates that the diameter of the improved guidewire proximal sectionD2 is 0.018.′ The function of the related art guidewire is both steeringand guiding, whereas the improved guidewire proximal section is used forsteering and the improved guidewire distal section is used for guiding.FIG. 9 includes an exemplary list of materials for both the related artguidewire and the improved guidewire (proximal section and distalsection). For example, the related art guidewire is generally made ofstainless steel. The improved guidewire proximal section may be made ofa stainless core wire with a coating, coil jacket or plastics tubingjacket. Alternatively, the proximal section may be made of a Nitinolwire or plastics string. The proximal section of the improved guidewiremay be coated. Similarly, the distal section of an improved guidewiremay be made of a stainless core wire with a coating, coils jacket orplastics tube jacket. Alternatively, the improved guidewire distalsection may be made of Nitinol wire.

FIG. 10 shows force metrics for a related art guidewire proximal section(e.g. 220 in FIG. 2) with an outer diameter of 0.025″ and for animproved guidewire proximal section with an outer diameter of 0.018.”The maximum backloading force through the pump when using the relatedart guidewire is 1.5 Newtons. This maximum backloading force issignificantly reduced to 0.3 N with the improved proximal guidewire.Furthermore, with the improved guidewire, a maximum sliding force forthe guidewire is reduced from 1.9 N of initial resistance to a 0.7 Nstable sliding force.

FIG. 11 shows a system 1100, with a percutaneous pump already backloadedon a guidewire according to one of the illustrative embodiments of FIGS.5-8, The system 1100 includes a guidewire 1102, a pigtail 1104 and acannula 1108. In the example of FIG. 11, the system 1100 is curved tofollow the shape of the pulmonary valve (not shown). As a physicianbackloads the pump and cannula 1108 onto the guidewire 1102, theguidewire 1102 passes through the pigtail 1104, through the cannula1108, and in the gap located between the blades and the housing of thepump.

FIG. 12 shows a method 1200 for inserting a percutaneous pump accordingto certain implementations, The method 1200 may be implemented to inserta percutaneous pump, e.g,, pump 101, onto a guidewire including but notlimited to the guidewires described in any of the aforementionedimplementations. The method 1200 may be implemented by inserting aguidewire, previously positioned into the artery of a patient, into acannula through a distal end of the cannula (step 1210), the distal endof the cannula supporting the percutaneous pump. The method 1200 furtherincludes pushing the guidewire through the percutaneous pump (step1220). The guidewire pushed through the percutaneous pump includes aproximal section with a first stiffness and a first diameter, and adistal section connected to the proximal section, the distal sectionwith a second stiffness and a second diameter greater than the firstdiameter. The distal section of the guidewire is stiffer than theproximal section to insert the cannula in a desired location withoutdisplacing the guidewire.

At least one benefit of the method 1200 is that it reduces the number ofinsertions of the guidewire into the patient, and minimizes the risk ofdamage to the patient's arterial system. The method 1200 usesbackloading of the guidewire to reduce the number of insertions into thepatient. Another benefit of the method 1200 is that it facilitatesinsertion of the guidewire into a pump, such as the pump 101 of theblood pump assembly 100. This reduces the risk of damage duringinsertion.

In alternative embodiments, the percutaneous pump may be backloaded onthe guidewire prior to the guidewire being positioned inside the arteryof the patient. In alternative embodiments, the percutaneous pump may bebackloaded on the guidewire before the percutaneous pump is coupled tothe cannula.

Variations and modifications will occur to those of skill in the artafter reviewing this disclosure. For example, in some implementations,any of the alternative embodiments described in FIGS. 5-8 may becombined. For example, the coil structure of the proximal end of theguidewire in FIG. 7 may be combined with the different guidewirematerials described with respect to FIGS. 5-6. In another example, thecoil structure of the proximal end of the guidewire in FIG. 7 may becombined with a weld transition described in relation to FIG. 6. Thedisclosed features may be implemented, in any combination andsubcombination (including multiple dependent combinations andsubcombinations), with one or more other features described herein. Thevarious features described or illustrated above, including anycomponents thereof, may be combined or integrated in other systems.Moreover, certain features may be omitted or not implemented.

It is important to note that the constructions and arrangements ofapparatuses or the components thereof as shown in the various exemplaryimplementations are illustrative only. Although only a fewimplementations have been described in detail in this disclosure, thoseskilled in the art who review this disclosure will readily appreciatethat many modifications are possible (e.g., variations in sizes,dimensions, structures, shapes and proportions of the various elements,values of parameters, mounting arrangements, use of materials, colors,orientations, etc.) without materially departing from the novelteachings and advantages of the subject matter disclosed. For example,elements shown as integrally formed may be constructed of multiple partsor elements, the position of elements may be reversed or otherwisevaried, and the nature or number of discrete elements or positions maybe altered or varied. The order or sequence of any process or methodsteps may be varied or re-sequenced according to alternativeimplementations. Other substitutions, modifications, changes andomissions may also be made in the design, operating conditions andarrangement of the various exemplary implementations without departingfrom the scope of the present disclosure.

While various inventive implementations have been described andillustrated herein, those of ordinary skill in the art will readilyenvision a variety of other mechanisms and/or structures for performingthe function and/or obtaining the results and/or one or more of theadvantages described herein, and each of such variations and/ormodifications is deemed to be within the scope of the inventiveimplementations described herein. More generally, those skilled in theart will readily appreciate that, unless otherwise noted, anyparameters, dimensions, materials, and configurations described hereinare meant to be exemplary and that the actual parameters, dimensions,materials, and/or configurations will depend upon the specificapplication or applications for which the inventive teachings is/areused. Those skilled in the art will recognize, or be able to ascertainusing no more than routine experimentation, many equivalents to thespecific inventive implementations described herein. It is, therefore,to be understood that the foregoing implementations are presented by wayof example only and that, within the scope of the appended claims andequivalents thereto, inventive implementations may be practicedotherwise than as specifically described and claimed. Inventiveimplementations of the present disclosure are directed to eachindividual feature, system, article, material, kit, and/or methoddescribed herein. In addition, any combination of two or more suchfeatures, systems, articles, materials, kits, and/or methods, if suchfeatures, systems, articles, materials, kits, and/or methods are notmutually inconsistent, is included within the inventive scope of thepresent disclosure.

For the purpose of this disclosure, the termed “coupled” means thejoining of two members directly or indirectly to one another. Suchjoining may be stationary or moveable in nature. Such joining may beachieved with the two members or the two members and any additionalintermediate members being integrally formed as a single unitary bodywith one another or within the two members of the two members and anyadditional intermediate members being attached to one another. Suchjoining may be permanent in nature or may be removable or releasable innature.

The indefinite articles “a” and “an,” as used herein in thespecification and in the claims, unless clearly indicated to thecontrary, should be understood to mean “at least one.” As used herein inthe specification and in the claims, “or” should be understood to havethe same meaning as “and/or” as defined above. For example, whenseparating items in a list, “or” or “and/or” shall be interpreted asbeing inclusive, i.e., the inclusion of at least one, but also includingmore than one, of a number or list of elements, and, optionally,additional unlisted items. Only terms clearly indicated to the contrary,such as “only one of” or “exactly one of” will refer to the inclusion ofexactly one element of a number or list of elements. In general, theterm “or” as used herein shall only be interpreted as indicatingexclusive alternatives (i.e. “one or the other but not both”) whenpreceded by terms of exclusivity, such as “either,” “one of,” “only oneof,” or “exactly one of.”

In the claims, as well as in the specification above, all transitionalphrases such as “comprising,” “including,” “carrying,” “having,”“containing,” “involving,” “holding,” “composed of,” and the like are tobe understood to be open-ended, i.e., to mean including but not limitedto.

The claims should not be read as limited to the described order orelements unless stated to that effect. It should be understood thatvarious changes in form and detail may be made by one of ordinary skillin the art without departing from the spirit and scope of the appendedclaims. All implementations that come within the spirit and scope of thefollowing claims and equivalents thereto are claimed.

Examples of changes, substitutions, and alterations are ascertainable byone skilled in the art and could be made without departing from thescope of the information disclosed herein. All references cited hereinare incorporated by reference in their entirety and made part of thisapplication.

1-18. (canceled)
 19. A guidewire for backloading a pump configured forpercutaneous insertion into a vascular system, the guidewire comprising:a proximal section with a first stiffness; a distal section with asecond stiffness greater than the first stiffness, wherein a thirdstiffness of blades of the pump is greater than the first stiffness. 20.The guidewire of claim 19, wherein the proximal section includes aproximal end and a distal end, the distal section includes a proximalend and a distal end, and the proximal end of the distal section isconnected to the distal end of the proximal section.
 21. The guidewireof claim 20 further comprising a soft distal tip at the distal end ofthe distal section.
 22. The guidewire of claim 19, wherein the thirdstiffness of the blades of the pump is greater than the first stiffnessso as to reduce damage to the blades when the proximal section of theguidewire is inserted into the pump.
 23. The guidewire of claim 19,wherein the proximal section and the distal section have differentdiameters that cause the second stiffness to be greater than the firststiffness.
 24. The guidewire of claim 23, wherein a ratio of a diameterof the proximal section to the diameter of the distal section is 0.72.25. The guidewire of claim 19, wherein the proximal section and thedistal section have different materials that cause the second stiffnessto be greater than the first stiffness.
 26. The guidewire of claim 25,wherein the proximal section comprises at least one of a stainless corewire, a stainless core wire with a coil jacket, a stainless core wirewith a plastics tubing jacket, a Nitinol wire, and a plastics string.27. The guidewire of claim 26, wherein the distal section comprises atleast one of a stainless core wire, a stainless core wire with a coiljacket, a stainless core wire with a plastics tubing jacket, and aNitinol wire.
 28. The guidewire of claim 27, wherein a diameter of thestainless core wire is constant.
 29. The guidewire of claim 28, whereina diameter of the stainless core wire increases distally.
 30. Theguidewire of claim 19, further comprising an intermediate sectionbetween the distal section and the proximal section.
 31. The guidewireof claim 30, wherein the intermediate section has a fourth stiffness,the fourth stiffness being greater than the second stiffness.
 32. Theguidewire of claim 31, wherein proximal section, the intermediatesection, and the distal section have differences in diameter that causethe second stiffness to be greater than the first stiffness and thefourth stiffness to be greater than the second stiffness.
 33. Theguidewire of claim 31, wherein the proximal section, the intermediatesection, and the distal section have different materials that cause thesecond stiffness to be greater than the first stiffness, and the fourthstiffness to be greater than the second stiffness.
 34. A method forloading over a guidewire, a pump configured for insertion into avascular system, the method comprising: inserting a guidewire into acannula through a distal end of the cannula, the distal end of thecannula supporting the pump; and pushing the guidewire through the pump,wherein the guidewire includes a proximal section made with a firststiffness and a distal section with a second stiffness greater than thefirst stiffness, wherein a third stiffness of blades of the pump isgreater than the first stiffness.
 35. The method of claim 34, whereinthe inserting the guidewire into the cannula comprises inserting theproximal section of the guidewire proximally into the distal end of thecannula.
 36. The method of claim 34, further comprising inserting theguidewire through empty space between the blades of the pump.
 37. Themethod of claim 34, further comprising inserting the pump into thevascular system of a patient.
 38. The method of claim 37, furthercomprising removing the guidewire from the vascular system of thepatient.